archive/File: remove unused attribute "plugin"

src/archive/ArchiveFile.hxx

@@ -27,12 +27,6 @@ class ArchiveVisitor;
 class InputStream;
 
 class ArchiveFile {
-public:
-	const ArchivePlugin &plugin;
-
-	ArchiveFile(const ArchivePlugin &_plugin)
-		:plugin(_plugin) {}
-
 protected:
 	/**
 	 * Use Close() instead of delete.

src/archive/plugins/Bzip2ArchivePlugin.cxx

@@ -46,8 +46,7 @@ public:
 	const InputStreamPtr istream;
 
 	Bzip2ArchiveFile(Path path, InputStreamPtr &&_is)
-		:ArchiveFile(bz2_archive_plugin),
-		 name(path.GetBase().c_str()),
+		:name(path.GetBase().c_str()),
 		 istream(std::move(_is)) {
 		// remove .bz2 suffix
 		const size_t len = name.length();

src/archive/plugins/Iso9660ArchivePlugin.cxx

@@ -45,7 +45,7 @@ class Iso9660ArchiveFile final : public ArchiveFile {
 
 public:
 	Iso9660ArchiveFile(iso9660_t *_iso)
-		:ArchiveFile(iso9660_archive_plugin), iso(_iso) {}
+		:iso(_iso) {}
 
 	~Iso9660ArchiveFile() {
 		iso9660_close(iso);

src/archive/plugins/ZzipArchivePlugin.cxx

@@ -40,7 +40,7 @@ public:
 	ZZIP_DIR *const dir;
 
 	ZzipArchiveFile(ZZIP_DIR *_dir)
-		:ArchiveFile(zzip_archive_plugin), dir(_dir) {}
+		:dir(_dir) {}
 
 	~ZzipArchiveFile() {
 		zzip_dir_close(dir);